General Category > Quadrajet Carb Talk and Tips
17077230 jet/rod sizes from the factory
quadrajam:
Set the idle as normal, use a vacuum gauge if it helps. If it runs good and dont skip or stink
leave it be. AFR meter best used for cruise and WOT on a warmed up engine. As far as engine damage....not gonna happen at idle or light loads.
QJ
Cadman-iac:
It does make your eyes water if you stand near the tailpipes when it idles, but it runs and idles great. I don't want it to wash the cylinder walls from too much gas, but I don't know at what point it would be too much.
My wife is complaining that she can smell gas, as if it were leaking, but I believe it's the exhaust she smells. I will check the fuel return line for leaks just in case. That's the only line that has any kind of pressure in it now.
The vacuum at 500 rpm in gear is 15 inches, and in park it idles at 600 with a vacuum of 16 inches.
I can set the AFR to 14.7 at idle but it doesn't run as smoothly as it does at an AFR of 12.5-13.0, and the vacuum isn't as high either.
Another question, at a part throttle cruise at around 3000 rpms, the AFR can go up to 16.0-16.5, which I think is normal for a light load at that rpm, isn't it? Or do I need to worry about that and adjust accordingly?
Thanks for any and all advice.
Rick
quadrajam:
When I work on my truck the wife complains of smelling $$$$$s,and they're flying away.
Hard to say from here, is there an old tank vent line still under the hood? Carburetors
can be smelly after a shutdown. Ignition timing can affect exhaust smell too. For sure
check for leaks. ???
QJ
Cadman-iac:
--- Quote from: quadrajam on February 19, 2025, 06:07:47 PM ---When I work on my truck the wife complains of smelling $$$$$s,and they're flying away.
Hard to say from here, is there an old tank vent line still under the hood? Carburetors
can be smelly after a shutdown. Ignition timing can affect exhaust smell too. For sure
check for leaks. ???
QJ
--- End quote ---
Lol!! Yeah, I get that too! But the tank vent line still goes to the vapor canister and is plumbed into the carb just like it is on the Cadillac engine. I took this off the Cadillac myself and made sure to make note of what went where.
I'm with you, I believe it's just the exhaust and maybe the carb. There's no vapor recovery for the fuel bowl on this unit, it apparently wasn't used in 77.
All of the fuel lines from the middle of this truck forward are new since the original TBI lines went up the back of the engine to the TBI unit. I had to make new metal lines and when necessary I installed new fuel hose. But those are very short, and I have a new flaring tool that can do the O-ring type ends, so my new lines match up with the remaining original ones.
Previously I had another carb on it that did have a bowl vent line and I used a canister that would accommodate that, but the canister was apparently previously fuel soaked and I wasn't aware of it until I had issues with the AFR fluctuating wildly. I pulled the suction line from the canister and it was dripping fuel, which is not supposed to happen.
So I switched carbs and canisters, the canister is the original one for the vehicle, it's an 88 Suburban that used to have a TBI unit on it. I know this canister is good and working correctly.
The only thing that I can think of that could possibly be leaking is the return line at the tank, and I'll check it out tomorrow.
I believe I'll have to tell her that it's just normal for a carbureted vehicle to smell a bit and to get used to it.
I did have a full tank of gas when I started replacing the engine and rebuilding it and the transmission, that was in June of last year. I've since added about half a tank that I've ran through it.
Would old fuel cause it to stink like that?
Kenth:
I have found that 1977-79 Cadillac 425 units has about .078" lower air bleeds and about .049" idle needle holes.
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